1. Yona Field, Subtropical Field Science Center, Faculty of Agriculture, University of the Ryukyus, Okinawa, Japan
2. Faculty of Agriculture, University of the Ryukyus, Okinawa, Japan
3. Forestry and Forest Products Research Institute, Ibaraki, Japan
4. Kansai Research Center, Forestry and Forest Products Research Institute, Kyoto, Japan
5. Kyusyu Research Center, Forestry and Forest Products Research Institute, Kumamoto, Japan